


Should Have Known You're Not Who I Thought

by literaryoblivion



Series: Tumblr Ficlets [96]
Category: Teen Wolf (TV)
Genre: Alternate Universe - Canon Divergence, Angst with a Happy Ending, Demonic Possession, Demons, First Kiss, Implied Sexual Content, Implied/Referenced Rape/Non-con, Light Angst, M/M, Possessed Derek
Language: English
Status: Completed
Published: 2015-05-30
Updated: 2015-05-30
Packaged: 2018-04-01 22:56:21
Rating: Teen And Up Audiences
Warnings: Underage
Chapters: 1
Words: 3,726
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4037722
Author URL: https://archiveofourown.org/users/literaryoblivion/pseuds/literaryoblivion
Summary: <blockquote class="userstuff">
              <p>“He was right about you; you are clever for a little sixteen-year-old boy.”</p><p>Stiles looks around himself, forever thankful he keeps a jar of emergency mountain ash on his person, since his bag is not within reach. The jar is empty now, and the ash is in a small, tight misshapen circle around him. He’s in a clearing of trees within the preserve, with no one else around and no one coming. He takes a look at his phone and of course there’s no signal, and everyone else thought he was fine cause he was going out with Derek. Which he did. Only…</p><p>“I knew possessing a werewolf would come back to bite me in the ass sometime. I was enjoying it so much though.”</p>
            </blockquote>





	Should Have Known You're Not Who I Thought

**Author's Note:**

> I got this prompt ages ago: "Sterek. Possessed!Derek who is taunting Stiles, while Stiles is trapped in a mountain ash ring. No one knows where they are so theres no help coming." This was started pre 3B, so this is a good old fashioned demon possession and not nogitsune funny business.
> 
> The tumblr post for this can be found [here](http://literaryoblivion.tumblr.com/post/120243995208/sterek-possessed-derek-who-is-taunting-stiles).

“He was right about you; you are clever for a little sixteen-year-old boy.”

Stiles looks around himself, forever thankful he keeps a jar of emergency mountain ash on his person, since his bag is not within reach. The jar is empty now, and the ash is in a small, tight misshapen circle around him. He’s in a clearing of trees within the preserve, with no one else around and no one coming. He takes a look at his phone and of course there’s no signal, and everyone else thought he was fine cause he was going out with Derek. Which he did. Only… 

“I knew possessing a werewolf would come back to bite me in the ass sometime. I was enjoying it so much though.”

“Why don’t you just come out of him then?” Stiles suggests. 

“Ahhh, nice try, baby. No… I think the super hearing and smelling are great perks. The fast healing also saves up my energy, so that’s convenient. Besides--” Derek, no, Not-Derek, walks up as close to the ash circle around Stiles as he can. Because of his hurry to throw it around him, it puts Derek close enough that Stiles can feel his breath as he continues. “I think I’ll stick around with this one for a little while longer. You weren’t the only one that liked him.” Not-Derek drags a clawed hand down his own chest and stomach, then drags it back up, letting his shirt ride up as he does, showing the defined abs that Stiles remembers all too well from the night before and a few nights before that.

He should have known then that something was up. Stiles feels like an idiot for not realizing it sooner. He should have seen that this wasn’t Derek. 

As if reading his mind, Not-Derek remarks, “Oh, don’t beat yourself up about it, kid. I wouldn’t have been able to resist this either if it gave me attention.”

“He’s not an ‘it,’” Stiles snarls. “You are, and if you know what’s good for you, you’ll leave him and me and everyone else the fuck alone.”

Not-Derek laughs. “Know what’s good for me? What are you going to do? No one is going to help you. You’re with me remember? Your precious Derek.”

Stiles narrows his eyes and glares at Not-Derek, but as much of a brave face as he puts on, the demon is right. He’s trapped in the circle as long as it stays there, and Stiles knows the demon is so much more powerful than even Derek. Stiles had witnessed it first-hand when he threw Stiles 30 feet in the air without even laying a hand on him. It had hurt, but it gave him enough time to throw the ash around him and pray that it would still work against a demon-possessed werewolf.

“You know, for as smart as Derek here told me you were, it sure did take you a while to put two and two together. You can’t tell me you honestly think he cared for you, did you?”

Stiles stares and refuses to let whatever this demon says get to him. It’s not Derek. It’s lying. Everything it says is a lie.

“Stiles, honey, I know what you’re thinking,” he says, and it helps Stiles remind himself that this isn’t Derek. Derek wouldn’t talk like that, wouldn’t call him things like _honey_. “I know you think I’m lying, but why would I lie to you? What good would that do me? You know he’s still in here, right? I can hear him, how disgusted he was when I kissed you, how much he hated me when we had sex. How much he hated you.”

“I don’t believe you,” Stiles shouts, his voice cracking just a bit, enough to make the demon laugh.

“Why would someone like him want to be with some snot-nosed obnoxious teenager? I, however, am not that picky. It was good, and I know you liked it. I think the whole neighborhood could tell you liked it, in fact. You sure are a screamer,” Not-Derek says with a smirk as he circles around Stiles.

Stiles hates this, hates himself too because of course Derek wouldn’t actually like him. He doesn’t want to believe this thing, but everything it’s telling him makes sense. Maybe it’s not lying. Maybe Derek really does find Stiles disgusting.

When Derek had crawled into his window a week ago, ignoring Stiles’s overview of research results about demonic possession to instead push him against the wall and kiss him until he was breathless, Stiles’s mind was obviously in another place. He had been too caught up in Derek finally returning his affections and his flirting, finally telling Stiles that he’d noticed that he’d wanted him as much as Stiles wanted Derek.

Stiles had asked why now? And Derek had told him about how he was worried because of their age difference, of the Sheriff, but that he couldn’t resist any longer. Not when Stiles was so obvious in pack meetings about his want for Derek.

It had clearly been a lie.

Derek is the master of self-deprivation, and if Stiles had been thinking with something other than his dick, he would have known then that Derek would have never made the first move, would have waited for years if Stiles let him. Deep down Stiles knew if he wanted anything from Derek, it was going to have to be him that actually said something, made his feelings for Derek known without any way for Derek to misinterpret them. 

It’s easy for Stiles to think that now, now that he’s trapped by a demon disguised as Derek. There were little things that had been off about Derek that whole week that Stiles was too lovestruck to put together. The things he’d call Stiles that sounded nothing like him, the smell of sulfur that even Stiles could pick up without werewolf powers, the all-too-brief moment while they were in bed that Derek’s eyes had been a color Stiles had never seen before—black.

And at the time, Stiles had thought he had just imagined it, but when Derek had left the morning after, saying he had some business to take care of and he’d pick him up later that night, Stiles saw his forgotten research on his desk. The research on demonic possession. Then it all clicked.

Stiles wanted it to be a lie; he didn’t want to believe that the whole week he had spent blissfully unaware fooling around with Derek wasn’t actually with _Derek_. But the longer he thought about all that happened, the more he hated himself for letting it all happen. He made a choice after doing some more research that he had to do something to save Derek, even if that meant Derek would never want to speak or talk to him again afterwards.

He tried to remain calm when “Derek” came to pick him up that night, pretending everything was fine. But, the demon must have picked up on something or had had his fun with Stiles because he started driving them off deeper into the woods and the preserve and farther from civilization. As soon as they pulled over, Stiles grabbed his bag and ran, which is why he then got picked up and thrown 30 feet away from his bag.

The bag that has everything he needs to severely injure a werewolf or incapacitate him and the chant to exorcise a demon. Something he’s regretting not memorizing right now as the demon continues to taunt and circle him, an ash barrier the only thing keeping them apart.

“Stiles, it seems we’ve reached a bit of a predicament.”

“How do you mean? You leave Derek and everyone else alone and go possess someone else that I don’t know or love, and we all go home happy. I see no predicament.”

“You’d really just let me leave? Just like that? I may look young in this body, but I’ve been around the block, sugar.”

Stiles eyes his backpack a few feet away, just out of reach. If he could just get to it, he could fix this whole problem.

“Deals,” Stiles says suddenly, and Not-Derek quirks his head. “Don’t you guys like deals? We could make a deal.”

The demon laughs, and it’s so unnatural seeing normally serious, scowling Derek laugh. Especially like that, laughter full of venom and mirth and spite.

“What, kid? Gonna give up your soul for lover boy here? Hate to break it to ya, but I’m not that kind of demon. Nice try. You don’t really have anything I want, so no dice, sweetie.” 

And Stiles, he’s not quite sure what makes him say it, desperation, love, the idea that he can’t bare to watch something else terrible happen to Derek without doing everything he can think of to fix it:

“What about me?”

Not-Derek stops his circling and stares at Stiles as if he’s trying to bore into him. “You,” he sneers out, and it sounds sarcastic and intrigued at the same time. “And why,” he starts, stepping so close to the mountain ash that he involuntarily winces when he hits the barrier, “would I give up the body of a werewolf for some useless, sniveling teenager?”

Stiles tries not to let the insult get to him. “I’m smart. I know plenty of facts and information about all sorts of creatures. Plus,” and he instantly regrets this before the words even come out of his mouth, “I’m the Sheriff’s son, so I can easily get access to things.”

Not-Derek lifts an eyebrow, like he’s considering Stiles’s offer. Finally, he smiles. “That’s very nice you, pumpkin, willing to sacrifice yourself for your wolfie loverboy. But, I think I’ll pass. Besides,” he says, taking a step back and holding his arm out, “I’m done playing, and I think it’ll be more fun to hear him scream while I kill you.”

Suddenly, Stiles is being thrown back out of the mountain ash circle. He lands hard on the ground on his back, right next to his bag. He reaches in, hoping to grab something useful, but the demon sees what he’s doing and launches the bag across the clearing and drags Stiles away from it towards him.

Not-Derek steps closer, a hand still up, and Stiles can feel it around his throat, squeezing tighter and tighter. He kicks his feet, struggling to regain his breath around the invisible force cutting him off from the air. He tries to open his mouth, to beg, to plead, he’s not sure, but nothing comes out but a harsh choked off noise.

“What was that?” Not-Derek says with a smirk, now leaning over Stiles, his outstretched hand slowly becoming a fist. As its fingers close, Stiles can feel himself slipping away, the pressure around his throat too much for him to try to breathe.

The force eases when Not-Derek’s face comes into view, his breath hot on Stiles’s skin. Stiles coughs and gasps for air while the demon will let him. “Any last words?” Not-Derek says with a smirk.

“I’m sorry, Derek,” Stiles whispers, hoarse and barely audible. The demon doesn’t seem to hear, or doesn’t care, and the pressure tightens.

In a last-ditch effort, Stiles shoves a handful of salt, the one thing he was able to grab from his bag before the demon had tossed it aside, into Not-Derek’s eyes. The demon screams and growls, causing Derek’s fangs and claws to extend without warning. The claws swipe across Stiles’s face, but not deep enough to cause any real damage but scratches. The demon tries to wipe the salt from his eyes and face, but his head snaps up as if he heard something.

Stiles barely registers a noise too, like a car door slamming, and then a voice that sounds like it might be Lydia spewing out words in a language he can’t understand. His brain is too foggy. He’s still trying to take in air and cough away the feeling of a hand closing around his throat to really comprehend anything else. 

He hears a deafening roar from Not-Derek and sees a plume of black smoke before everything in Stiles’s vision goes black. 

~

He wakes up in his bed to the smell of acetone and nail polish, which he supposes is better than what it could be… like sulfur. He slowly turns his head to see Lydia sitting in his desk chair next to him, using his nightstand as a makeshift vanity. She’s painting her nails a vivid red, and she doesn’t even seem to notice he’s awake. But then without looking away from her nails, she says,

“Finally. I thought I was going to have to be here all day.”

“I’m glad to hear you care so much about me.” When he speaks, it makes his whole throat hurt and ache, and his voice sounds scratchy like he’s getting over a cold. 

“If I didn’t, I wouldn’t be here right now,” she snaps at him. 

Stiles holds his hands up, not wanting to incur the wrath of Lydia before he even registers what day it is. Slowly, he sits up, accepting the water bottle Lydia holds out for him.

“So?” Stiles asks after downing half the water.

“So,” Lydia parrots back as she closes the bottle of nail polish. Stiles watches as she blows lightly on her freshly painted nails, waiting for her to fill him in, to give him answers to the questions he hopes he doesn’t have to voice.

“Derek’s fine,” is the first thing Lydia says. Stiles shrugs, pretending that wasn’t the first thing he wanted to know about, but it was and he’s relieved.

“Thankfully,” Lydia continues, “I was doing my own research and came to the same conclusion you did. Only I _told_ everyone else about it instead of trying to take care of it on my own.” She says it like she’s reprimanding him, and honestly, he gets it. She’s saying it because she cares, because she was worried about him. He doesn’t appreciate the scolding tone, but he’s still too weak and tired to comment on it.

“Anyway, it was a good thing I did, or else you and Derek both would have been gone. So you’re welcome.” She stands like she’s finished, like she’s explained enough and she has more important things to do. 

“Thanks,” he says, a small smile on his lips, one she returns. She gives him a quick hug and peck on the cheek.

And just as quickly as it appeared, the sincere smile is gone and she’s crossing the room toward the door. “You probably would have gotten the Latin wrong, anyway,” she says, flipping her hair as she opens his bedroom door. 

“Lydia?” he asks, stopping her from disappearing down the hall. “Derek’s really okay? Did he… say anything about… what happened?”

Lydia frowns and shakes her head. “But he’s been texting me non-stop to see if you’re awake and okay, so I’m sure you’ll be seeing him soon.”

About ten minutes after Lydia leaves, his dad walks in with a bowl of soup. He’s figured Lydia has already filled him in on what all went down, but he hopes she left out the part where him and Derek were a thing before this happened because that is something his dad definitely didn’t know about.

“How you feelin’, kiddo?” his dad asks, placing the bowl in Stiles’s hands.

“Sore,” he replies, smelling the soup and just now realizing how hungry he is. He practically inhales spoonfuls, and his dad chuckles at the sight.

“Too sore for visitors?”

Stiles furrows his brow and he sets his spoon down. “No?” he replies, because he did just have Lydia in his room, but then again she was playing his nurse not really visiting. It’s probably Scott, anyway.

The Sheriff narrows his eyes at him and nods. He watches as Stiles finishes off the soup, and the Sheriff takes his bowl back from him. “I’ll send him up, but he can only stay for a little bit.” When he’s at the door, he adds, “And don’t think we’re not going to be talking about this.”

“Got it,” Stiles sighs, knowing that no matter what Lydia told his dad, he’d want to know the whole story from Stiles himself.

There’s a soft knock on his door before it slowly swings open. It’s not Scott.

“Hey,” Derek says when he comes into view.

“Uh, hey?” Stiles says, tentative because he’s not sure where they stand now with everything that’s happened.

Derek nods and shuffles into the room and stands there as if ready to sprint out the door if Stiles told him to.

“How are-- Are you… okay?” Derek asks, not-so-subtly looking him over. 

Stiles shrugs. “I’m alive, so that’s good.”

Derek looks down, his face clearly upset, like he’s blaming himself for what happened. And of course he is. It’s such a Derek thing to do.

“It’s not your fault, you know.” 

Derek refuses to look at Stiles, and Stiles takes it to mean he doesn’t believe him.  

Slowly, he gets up from the bed and crosses the room to stand in front of Derek. “Hey,” he says, and Derek looks up then. “You had nothing to do with this. I’m okay.” He takes a moment to stare back at Derek, to make sure he heard him. Then he asks, “Are _you_ okay?”

“I… I’m alive,” he answers, and Stiles can tell he means it as a joke, but it’s too filled with relief to be. He stiffens when Stiles shifts closer, so Stiles steps back. 

“Good,” Stiles says with a tight grin. He can tell Derek would rather be anywhere but here now that he’s made sure Stiles was okay. “Well we can be near-death but still alive buddies,” he says, sitting back down on the edge of his bed. He hopes Derek will take it as a cue that he can leave now because with everything that’s happened, Derek forcing himself to be in Stiles’s company when he clearly can’t stand it is the last thing Stiles wants to witness. Guess the demon hadn’t lied about some things.

“Stiles, I… I’m sorry for what happened, how--”

“I get it, Derek,” Stiles cuts him off. “It wasn’t you. Not your fault, remember? I’m sorry I didn’t catch on sooner, then you wouldn’t have had to… Just, we can forget about it and go back to being friends, or tentative acquaintances, whatever it was we were before.” 

Stiles takes a chance at looking at Derek, and he’s not quite sure why Derek looks confused. “Or not? We could be nothing?” Stiles suggests, not hiding the hurt he feels when he says it. “I mean I understand if you don’t want to see me because who would want to see the person they were forced to have sex with? Geez,” Stiles says, burying his head in his hands.

“Stiles,” Derek says, suddenly much closer, and his hands are around Stiles’s wrists, tugging gently to get him to look at him. “ _Stiles_ ,” he says, a little more insistent, and Stiles finally looks at Derek, his eyes wet with unshed tears. Derek is kneeling in front of him, and Stiles thinks he sees hope in his face instead of the regret he was expecting. 

“Is this because of what the demon told you?” Derek asks.

“You remember all that? You heard it?” 

Derek nods. “I was in there, but it was like I was trapped, like I just had to watch while someone else pulled the strings.” 

“What it said… that you were disgusted while we…” Geez, he can’t even say it because it hurts to even think about. It had been such a happy memory, but now that entire week, every moment that he had been with Derek in what he thought was the start of a relationship, was tainted. 

“I was, but not because of you, not because you were with me, but because it wasn’t actually me. I… I like you, Stiles. I have for a while, and it used that against me, because it got joy out of making me watch it take advantage of you. It took all those firsts away from me, away from us, and I tried. I tried so hard, Stiles, to make it stop, to let you know that it wasn’t me, but I couldn’t.” His voice is getting angry now, gaze focused on the ground. “I couldn’t do _anything_ to stop it, not when we were… or when it was choking you. I was so useless, and I couldn’t save you--”

“Hey,” Stiles says, cupping Derek’s jaw and forcing him to look up. “It’s okay. We’re alive, yeah?” Derek’s head nods slightly in Stiles’s hands. “You’ve liked me for a while?” Stiles asks, a small grin forming on his lips.

Derek rolls his eyes. “Out of all that, that’s what you pick up on?”

“Don’t dodge the question.”

Derek sighs, “Yeah. I have. I do. Like you.”

“Think we could re-do our firsts? Like a do-over where we are both us?”

Derek smiles and leans in closer, their mouths inches apart. “Yes. Which first should we start with?” He’s close enough that Stiles can feel Derek’s breath on his lips.

Stiles doesn’t dignify the question with a verbal answer and instead, closes the distance between them and kisses Derek.

It’s perfect and unhurried and soft, which is so different and so much better than his first kiss with Not-Derek had been. Part of Stiles is mad at himself that he didn’t know then that it hadn’t been Derek, but he lets it go when Derek gently pushes him back to lay down on the bed and covers him with his body.

Before it can get heated, which it is already starting to with Derek laying on top of him and rolling his hips, Stiles pushes on Derek’s chest to make him stop and pull back.

“Maybe we should save our other firsts for a time when my dad isn’t downstairs?” Stiles says, breathless. 

Derek nods and ducks down for another kiss before climbing off of Stiles and his bed. “You should rest some more anyway.”

“See you tomorrow?” he asks, propping himself up on his elbows.

Derek leans over and gives Stiles another kiss. “See you tomorrow.”

**Author's Note:**

> Come say hi on [tumblr](http://literaryoblivion.tumblr.com) or [twitter](http://twitter.com/lit_oblivion).


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